Cavity-coupled plasmonic structure is demonstrated to be a simple and effective tool to manipulatelight, enhance the biosensing figure of merit, and control the polarization state. In this Letter, we demonstrate the tunability of the chiroptical effect of cavity-coupled chiral structure, i.e., sandwich chiral metamaterials (SCMs), in whichradiation coupling dominates the interaction between particles. Two types of SCMs whose building blocks are 3D chiral and 2D chiral, respectively, are numerically studied. Distinct responses are observed in these two materials. The chiroptical effect can be effectively manipulated and enhanced in the 2D case, while the SCMs consisting of 3D chiral layers keep the chiroptical effecta constant. A theoretical analysis based on matrix optics is developed to explain the corresponding phenomena, which gives a reasonable agreement with numerical simulations.